Freaky,
It is a castor/ synthetic blend, how-ever , it doesnt gum things up like Castrol R does after a while , but I dump it after the meeting as well as carb and fuel tank, part of post meeting maintaince, It does go milky if you over fuel your motor, ie way to rich, having said that, spoken to Sprintcar driver mate that runs the oil and Alky in the motor, he says the milkiness doesnt affect the oil and so does another GP midget driver mate of mine, and I have been running it for a while now and it hasn't affected my motors, Castrol Edge Sport 25w50 is a replacement for Castrol GP 50 which I used up until its replacement.
Check it out on Castrol's website.
I think it is cheaper than Shell M we use in TD's 84s, but my motors are Yammy 500s so was looking for an oil that suited recirculating oil systems
Foss